High Speed Photometer

The simplest of the five original scientific instruments on board the Hubble Space Telescope, the High Speed Photometer had no moving parts. Its five detectors measured the brightness of celestial objects in several different spectral bands in the ultraviolet, as well as their brightnesses in visible wavelengths. With funding provided by NASA, the Photometer was built at the University of Wisconsin, Madison, by astronomers, engineers, technicians, and students at the Space Astronomy Laboratory and the Space Science and Engineering Center. Measuring 3 by 3 by 6 feet, HSP is about the size of a telephone booth and weighs 600 pounds.

The HSP was sacrificed to make room for the device intended to correct the catastrophic error in the primary mirror. When the HSP was removed to make room for COSTAR, it was the only instrument on board not to have suffered a failure of a major subsystem.

Astronomy with HSP

The High-Speed Photometer (HSP) investigation made fast-time-resolution (down to 10 microseconds) photometric observations of rapidly varying objects in the spectral range 1150 to 8700 A and linear polarimetric observations from 2100 to 7000 A of a wide variety of objects. The instrument consisted of four image dissectors: two sensitive in the UV and solar blind, the others sensitive in the visible and near infrared. A wide variety of bandpasses is formed by broadband and interference filters arranged in strips near the HST focus. Some of the filters are coated with a polarizing material. Apertures provided a choice of three fields of view: 0.4, 1.0, and 10.8 arc-s. The dissectors could be commanded to receive photoelectrons from any of the approximately 100 filter-aperture-polarizer combinations available.